1. Field of the Invention
The present invention relates generally to a Printed Circuit Board (PCB), and more particularly, to a PCB with a double structure provided by printing conductive ink/paste on a substrate and through electroless plating or electrolytic plating of a high-melting point metal thereon, and a method for manufacturing the same.
2. Description of the Related Art
Technology has recently been introduced that replaces copper cladding, which is a material used for a circuit pattern, with conductive ink/paste in an attempt to manufacture low-priced PCBs. The conductive ink is made by commonly dispersing metal particles having a diameter of several to several tens of nanometers in a solvent. When the conductive ink is printed on a substrate and heat is applied thereto at a specific temperature, organic additives such as dispersing agents are volatilized and gaps between the metal particles are contracted and sintered, forming conductors which are electromechanically connected to each other. The conductive paste is made by commonly dispersing metal particles having a diameter of several hundreds to several thousands of nanometers in an adhesive resin. When the conductive paste is printed on the substrate and heat is applied thereto at a specific temperature, the resin is cured and electromechanical contacts between the metal particles are fixed, forming conductors, which are connected to each other. A PCB with a circuit pattern made of conductive ink/paste is illustrated in FIG. 1. A circuit is formed by printing conductive ink/paste 2 on a polyimide substrate 1 in a predetermined pattern, and sintering the conductive ink or curing the conductive paste, by applying heat thereto in a specific condition.
However, while parts are adhered to the circuit pattern using solder, the circuit pattern may be melted down together with the solder due to a low melting point of the conductive ink/paste. Conventionally, a method of adhering parts to the circuit pattern using conductive adhesive was used to address this problem. In FIG. 1, part 4 is adhered to a circuit pattern 2 by applying a conductive adhesive 3 onto the circuit pattern 2 formed of the conductive ink/paste in a dispensing manner (not shown), and then curing the conductive adhesive 3 through the application of heat or ultraviolet rays. However, the dispensing process for conductive adhesive results in a significantly lower productivity than a Surface Mount Device (SMD) process achieved using solder. Further, the storage property of a material for the conductive adhesive is poor, and the material for the conductive adhesive is remarkably higher than the solder in price.
For the general PCB with a circuit pattern made of copper cladding, a double structure is well known that prevents the circuit pattern from being melted down together with the solder by plating a high-melting point metal on the circuit pattern to adhere parts onto the circuit pattern.